Joint for oil-filled cables and method of building it



I 2 Sheets-Sheet" l INVENTOR m .mi

K. MILLER Filed Sept. lO, 1927 JOINT FOR OIL FILLED CABLES AND METHOD 0F BUILI'JIING IT nwmwhw Sept. 16, 1930. K. w. MILLER l 1,775,127

JOINT FOR OIL FILLED CABLES AND METHOD 0F BUILDING IT Filed sept. 1o, 1927 2 sheets-sheet 2 connector Sheath Stro( hk Portion 'Ta-ered Portion Patented sept. 16, '1930 UNITED STATES l PATENT o1=1=1 c1:

KENNETH W. MILLER, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GENERAL CABLE CORPORATION, A CORPORATION F NEW JERSEY JOINT FOR OIL-FILLED CABLES AND METHOD OF BUILDING IT Application led September 10, 1927.

My invention relates to the building of joints for oil-filled, high-tension electric cables, and consists in improvements in the apparatus, method, and product disclosed in 5 Letters Patent of the United States No.

1,585,127, granted May 18, 1926, on the application of Donald M. Simons and Frank l). Barbour; No. 1,613,911, granted January 11, 1927, on the application of the said Simons;

,10 No. 1,642,514, granted September 18, 1927, on theapplication of the said Simons, and No. 1,642,515, granted September 13, 1927, on the application of the said Simons.

My invention is illustrated in the accompanying drawings. Fig. 1 is a. diagrammatic View in longitudinal and axial section of the finished oint, built according to and embodying my present invention. Fig 2 is a view in plan of apreformed Web of flexible insulating a) material, in its shape embodying features of my invention, which in the building of the joint is Wrapped to place around the electrically connected conductor ends. Fig. 3 is a vieW to larger scale, illustrating diagrammatically and in detail, a certain feature of constructionachieved in the use of the web ot' Fig. 2. Figure 4 is a diagrammatic view illustrating the application of the Webs ot flexible insulating material in the building of a joint.

According to the disclosure of the Simons Patent No. 1,613,911 mentioned above, a tank is provided With opposite endrwalls adapted to receive and engage in 1i uid tight closure upon them two cable ends to united. These cable ends are by the engagement of the end Walls of the tankheld to axial alignment. The patent describes the preliminary ex osure of t-he conductor ends, before the' ca le 4o ends are introduced within the tank; it describes the electrical connecting of thefconductor ends Within'the tank, the cutting back of the ends of the envelopes of machine-laid insulation, and the wra ping upon connecter and betweenthe ends o the envelopes of machine-laid insulation, and under oil, a Web of flexible' slieetinsulation. The tank contains a rotary cage, rotatable upon the axis of the cable structure under treatment, and the cage carries the sheet insulation in a roll and in the Serial No. 218,793.

progress of operation this sheet insulation is unwound from the roll and Wound upon the cable structure. It is with the joint so built and with the `machinery for and the method of building that my invention has to do.

According to the teaching of Patents 1,585,-

127 and 1,613,911 mentioned above, the ends of machine-laid insulation are prepared for the wrapping on ot' a web of sheet insulation between them by cutting them either into successions of receding steps or into tapering conical or penciled form and the Web of sheet insulation is correspondingly cut, to lit the space between the opposed ends of the two envelopes ot machine-laid insulation and in a single Wrap to iill all the space. The pencled formation is preferable to the stepped formation; the riser of the step is of no electrical consequence nor advantage; 1t is the tread of the step, the surface which extends in parallelism with the cable axis.,

upon which electrically secure union is made; and I find that a web Wrapped under oil upon a penciled end of the envelope of machinelaid insulation, particularly it the penciling be done and the Web of AWrapped-on material be shaped as herein described, will be electrically and mechanically secure, and capable of practical and economical production.

A In the diagrammatic showing of Fig; 1, illustrative of the finished joint of my invention, the sheath of the cable end is indicated at 1, and the joint casing Which at vits ends is mechanically united to the ends of the `cable sheath, is indicated at 2. Within the' sheath the bared conductor ends have beenv electrically joined Within the connecter 3. The ends of the lenvelopes of machine-laid insulation have been laid back in the tapered or penciled configuration 4, and upon the connecter 3 and the penciled ends 4 of the en-l 6 of hand-Wrapped tape, building out a sury face to afford continuous gradient frompencil 4 to the essentially cylindrical surface of connecter 3. There is inthis hand-wrapping 6 (and in the first few turns in the building' of body 5 as Well, underpracticalconditions) the chance that small bubbles of air or of 'moisture may occur. But, as compared with hand-taping, that chance, which in handtaping attends the whole operation, is inl the practice of my invention limited to a rela'- tively small region. Furthermore, the 'volurne of air or of moisture which mayA possibly l l be so included, is Iso small that with good,

dry de-aerated (or even plain) oil, any bubble will soon diffuse and be absorbed intov the -Wh'ole body of insulation, and practically cease to exist. It is in the surface '4 where my invention c entersaboth in the pencil'ing Qf-fthe envelope of machine-laid insulation, and in the-,shaping ofthe body 5 to it.

In the oil-filled cable the body of machinelaid insulation'is formed` of ,paper wrapped ,helically`to,place, and saturated with oil of high dielectric strength. All the space Within`the. sheath not occupied by conductor and by paper, is flushed with oil. The material which in the 'operation of joint building is Wrapped under oil to. form body "5 is preferably' varnished cambric. l

The'web of varnished cambric for building the body 5 of Fig.. l is shown diagram-- matically in plan in Fig. E2. 'Its overall'dimensions are 501/2 feet X 36 inches. The` cambric is' rcut on the bias', and the seams 7 eX- tend obliquely to the length. The portion 8- is that which, when wrapping has been effected, immediately,surroundsthe connecter and fills the space between the penciled ends of the insulating envelopes. The portion 9 forms the enlargement of the body() beyond the diameter of the'bodies of machinel'ai'd insulation,

Aand,'for the purpose of limiting dielectric stresses, the edges of the portion 9 andthe outerend of the portion 9 may be metallized.

It isgwith the 'portion 8 that my'present invention has more particularly to do.

The web is cut .throughout the extent of ortion 8 a little too wide, a little over-size. n consequence, when the web is wrapped to place, its medial portion will lic in prrallelism with the surface of the conductor. but the edges ofportion 8 will spool up slightly .on the penciled surfaces 4. "T his, however, is

advantageous. It affords the best bearing of surface upon'surface, where such`bearing is needed, and while accomplishing 111s it does not cause voids to occur in medial portions of the Wrap.

` The cutting of the pen'ciled surface 4 is advantageously effected by instrumentalities which take their position by bearing upon connecter 3. The surface 4 accordingly may under practical conditions deviate minutely.

from a perfect cone, precisely coaxial with the cable structure. wButsuch small irregularities'will have no serious nor appreclable disturbing effect upon the dielectric field, for

the web of varnished Vcambric as it i's'wra'pped will adjust itself perfectly to them.' And when the great 4saving of time which may be account, and Vwhen it is remembered that the longitudinal slope of the pencil is 'uniform and that the cutting isaccomplished withvrealized in cutting the pencil is taken into out any trapping of' air undery the edges of the paper, the very slight occasional eccentricity of the pencil is ania-tter of no ap,-- preciable moment. The only electrical vef- 'fect of such slight eccentricityfwillbea very small but smooth shift of'voltage stresses. The location and accuracy of the pencil will be much more perfect than the circumstances require.

The varnished cambric may be about 0.011

` ofan inch thick; the gradient of the penciled slope 4 may be 1:18. Each edge ofbody '5 then should widen about 0.2`of an inch for levery added layer. 1 preferably .form the body -5 of two webs wrapped together-and accordingly each web should widen at a rate of about 0.4 of an inch on 'each side for every turn. When two webs are wrapped together to form a body 5, they are laid down at diametrica'lly opposite points.

To avoid trouble due to errors of a fraction.

of a turn in starting the two rolls of cambric in the wrapping operation, the gaining of one rollY upon the other because of inequality in tension. and'to afford correction for 'anyslight shifting of the rolls of cambric longitudinally upon-the cage which carries' them,- but chiefly to get widened surfaces of bearing in planes parallel to the axis of the cable structure-I adopt the minute shaping of the edge of the wrap, particularly in the portion' crease in correspondence with the enlargement of thecircumference of the wrap, but should average, approximately, from a half to three quarters of an inch on the main line of' increase of width. I have said that I preferably lbuild the body 5 of two webs of cambric and when two webs are employed, one edge only of the portion 8 of each web need be scalloped. The opposite edge may, as shown in Fig. 2, be straight. In application, the scalloped edges of the two webs comes to place one on each of the two opposite' penciled surfaces 4, and', considering either 7;'

lUJ

The

Vwill average out over a succession of turns,

and the scallops will lap one over another, like the feathers of a bird, or like the shingles on a roof. And since the webs have intentionally been cut slightly over-size, the bearing upon the underlying penciled surface 4 will be perfect. The elasticity of the cambric will give intimate Contact across the width of the wrap, and the oil in which at the time of wrapping the work is submerged, will afford perfect filling. ySuch an application of two webs 'in the building of a joint is diagrammatically illustrated in Figure 4 of the drawings. The two webs are here shown to be superposed, each has one edge scalloped. One web is scalloped along one edge, the other web isscalloped along the opposite edge, so that the assembly shows a line of scallops along each of the two edges. The webs at their ends are applied to the connector 3 and then they are wrapped upon the connector 3 and upon and between the penciled ends 4 of the bodies of insulation of the two cable ends whose conductors are united in the connector 3.

While I have in Figure 4 diagrammatically shown the two webs as brought together and applied together, and while this particular arrangement is entirely possible, I prefer to build the body `5 of two webs of cambric applied at diametrically opposite points, first,

because, in consequence, the overall diameter of the joint-building machine may be reduced; second, beca-use the oppositely applied 'tnsions of the two wraps counter- -balance one another; third, the twists on thc two tension brakes, which conveniently are mounted both on one cage head, tend to balance one another, and accordingly the cage head may be built of lighter material; and, fourth, the individual webs are each but half as long as a single web must be, and the wrapping may be done at double speed.

I claim as my invention:

l. The method' herein described of building a body of insulationy in electrically secure abutment upon .an inclined surface, which consists in vsuperposing under Voil layers offsheet insulation with scalloped edge` the so successively superposed scallops of the layersl being out of register one upon anotherandfoverlapping lengthwise of the sheet upon such inclined surface.

2. The method herein described of building a body of insulation in electrically secure abutment upon an inclined surface, which consists in superposing layers of sheet insulation with edges alternately straight and scalloped, the so successively superposed scallops of the edges of the sheet insulation being out of register one upon another, the edges of the layers lapping lengthwise of the sheet upon such inclined surface.L

3. The method herein described of building a wrapped-on body of insulation around a conductor and in electrically secure abutvnient upon an envelope of machine-laid 1nsulation with which the conductor is adjacently surrounded, which consists in penciling the end of the body of machine-laid insulation and wrapping upon the conductor a scalloped-edged web of sheet insulation, such scalloped edge of the web overlapping lengthwise of the web as the successive layers are wrapped upon the penciled surface of the envelope.

4. The method herein described of building a wrapped-on body of insulation around a conductor` and in electrically secure abutment upon an envelope of machine-laid insulation with which the conductor is adjacently surrounded, which consists in penciling in a rippled surface the end of the body` of machine-laid insulation and in` wrapping upon the conductor a scalloped-edged web,

of sheet insulation, such scalloped edge of the web overlapping lengthwise of the webv as the successive layers are wrapped upon the.'

'side of the electrically connected conductor ends, and wrapping upon the connected conductor ends and between the penciled envelope ends a scalloped-edged web of flexible sheet insulation, with scallops overlapping lengthwise of the web as the successive layers are wrapped upon the penciled envelope ends.

6. In an electrical installation two bodies of insulation overlying a conductor and meeting on a surface oblique with respect to the surface overlaid, one of said bodies being built of laminate scalloped-edged sheet insulation, the sheets throughout their medial portions extending in parallelism to the surface of thev con'ductor, and the scallops of the edge overlapping lengthwise of the web as the successive layers are wrapped upon the other body in the oblique surface of meeting.

7. In an electrical installation two bodies of insulation overlying a conductor and 8. In a cable oint and in combination with connected conductor ends, envelopes of machine-laid insulation oppositely peneiled at predetermined spacing one from the other on '5 either sideof the connected conductor ends,

" and a wrap of flexible scalloped-edge sheet insulation encircling the connected conductor ends and filling the space between the .pen-

ciled envelope ends and over-lapping marginally upon the pencilled envelope ends.

9. The method herein described ofbuilding a body of insulation in electrically secure abutment upon an inclined surface, which consi'sts'in superposing layers of sheet in sulation with scalloped edge, the so succes sively superposed scallops of the successive layers being out of register one upon another and overlapping lengthwise of the sheetV upon such inclined surface.

l '10. A-wrapping for a cable joint compris; ing a sheet of insulating material, the sheet being tapered towards one end and one of the edges extending in sinuous line.

- 1l. A wrapping for a cable joint compris- 25,ing' a sheet of insulating material tapering withv scalloped edge towards one end. v

12. Awrapping' for a cable joint comprising "two tapering sheets of insulating ma'-' terial one edge of'each extending Vin sinuous course, the .two sheets being assembled to form'a dou-blewra-p and in assembledposition presenting their sin'uous edges one along onel side the other along the other. side of the assembly.

13.*A wrapping for a cable joint comprising a sheet of insulating material, the sheet being tapered towardsvo'ne end and one edge of the. tapered portion, by departure from a straight line, being formed with alternate {40f extensions and recessions. v

In testimony whereof I have hereunto set my hand.

- KENNETH W. MILLER. 

